Energy expenditure after infusion of glucose-based total parenteral nutrition.

Resting energy expenditure (REE), carbohydrate balance, and lipogenesis were calculated after administration of glucose-based total parenteral nutrition (TPN) to determine whether the thermic effect of glucose is equal to the energy cost of storing the glucose. Estimated cost of storage as glycogen (5.3%) and fat (19%) was compared with measured increases in REE. Patients with malnutrition received 5% dextrose in water and 6 days of TPN with a low (1.2 times REE, group 1) or high (2.0 times REE, group 2) level of glucose intake. Increases in REE by day 6 were 10% (group 1) and 28% (group 2). The theoretical cost of glucose storage as glycogen and fat accounted for approximately 40% of the measured increase in REE in patients in group 2. The thermic effect of TPN (derived from patients in group 1) accounted for most of the balance. The majority of the thermic effect of high levels of glucose infused with TPN can be explained on the basis of the thermic effect of TPN and glucose storage.